Voltage dividers are typically produced by connecting two partial resistors in series, at the common connecting point of which part of the voltage applied to the series circuit can be output. As a rule, one end of such a series circuit of the two resistors is connected to a low potential whilst the other end of the series circuit is connected to a point in the circuit of higher potential, the ratio of the drop in voltage across the one partial resistor as compared to that of the other corresponding to the ratio of the resistor values.
When a voltage divider of the aforementioned kind is used to divide a high frequency voltage or a square-wave voltage having a steep slope, the unavoidable stray capacitances accompanying the partial resistors become a disadvantage since the waveform of the divided voltage no longer corresponds to the waveform of the input voltage of the voltage divider. With square-wave voltages these stray capacitances lead, for example, to a more or less pronounced overshoot on the pulse slopes. In a voltage divider used as the input divider of an oscilloscope this behaviour is particularly a nuisance since the negative effects of the stray capacitances are directly evident on the screen, the viewer then not knowing whether he is seeing the correct signal shape corresponding to the input signal or a signal shape which is changed due to the stray capacitances. The effects of the stray capacitances are all the more serious, the higher the frequencies involved and the higher the impedance of the partial resistors.
For frequency compensation of the voltage divider the partial resistors can each be connected in parallel with capacitors which are dimensioned so that the products of the resistor value of the partial resistor and the correspondingly assigned capacitor are the same.
When producing a voltage divider in integrated circuit technology the frequency compensation cannot be attained by connecting the integrated capacitors in parallel with the integrated partial resistors. In the case of integrated partial resistors the stray capacitances are distributed over the full geometrical area of the resistor body and they must not necessarily be located between the two ends of the partial resistor. Apart from this, a considerable stray capacitance with respect to GND exists.
An object of the invention is to create an integrated voltage divider of the kind as mentioned at the outset, the output voltage profile of which represents the input voltage profile irrespective of the frequency of the input voltage.